Fuel injection pumps have control levers which are engaged by a positioning element, typically a push rod. The push rod can be part of a centrifugal controller and thus both rotate as well as move axially. The engagement area between the push rod and the control lever as such is subject to wear.
In one arrangement of control levers, tensioning lever and a start lever are pivotable about a common axis which axis is pivoted in an adjustment lever structure which, in turn, is pivotably secured in the housing for the fuel injection pump. In operation, the housing is filled with the fuel to be injected. The tensioning lever can be positioned within a positioning lever by means of a control spring. The positioning element, is in continuous engagement with the start lever. The positioning element may be in form of a rod or bushing which is in engagement with the start lever. A spring between the tensioning lever and the start lever causes continuous engagement between the start lever and the positioning element.
The engagement surfaces of a start lever with the positioning element, usually are made of the same material as the lever itself. The start lever typically is a drawn steel element or a pressure cast element. Although the materials used for the start lever can be quite hard, the engagement surface is still subject to excessive wear upon continuous rotary and axial movement. The increased wear of the engagement surface of the continuously rotating positioning element with the surface of the start lever may change the respective positional relationship of the start lever with respect to the positioning element and thus may introduce an undesirable bias tolerance, that is, an undesired, uncontrolled mislocation of the start lever which may cause decrease of the fuel being injected by the fuel pump due to inaccurate control of the quantity of fuel. This inaccurate control may be due to shift of the position of the start lever due to such wear.